Effecting interchange of electric charges between solid conductors and gases.



P. G. GOTTRELL. EPFEGTING INTEBGHANGE 0F ELECTRIC CHARGES BETWEEN SOLID GONDUGTORS AND GASES.

APPLICATION FILED JULY 13, 1908.

W/WM 5 7544 COTTRELL, siding at Berkeley,

have this in common,

' with sharp metallic points,

UNITED STATES PATENT ornion.

REDERICK GARDNER COTTBELL, OF BERKELEY, CALIFORNIA, ASSIGNOE TO INTER- OF SAN FRANCISCO, CALIFORNIA, ACOR- NATIONAL PRECIPITATION COMPANY, POBATION OF CALIFORNIA.

EFFECTING INTEBCHANGE OF ELECTRIC CHARGES SOLID CONDUCTORS AND GASES.

To all whom it may concern:

Be it known that I, FREDERICK GARDNER a citizen of the United States, rein the county of Alameda and State of California, have invented certain new and useful Improvements in Efiecting Interchange of Electric Charges Between Solid Conductors and Gases, of which the following is a specification.

My invention relates to the art of transferring or interchanging electric charges between solid conductors and gases. It is'applicable to a wide range of-technical operations, as, for instance, electrostatic ore-separation; the manufacture of ozone; the operation of electrostatic generators or influence machines, and, as I D scribed in a co-pendin application, Serial Number 382,928 filed uly' 9, 1907, the precipitation of sus ended matter from gases.

Operations 0 the above mentioned types depend upon the passage of electricity between solids and gases, this passage must be prevented from taking-the form ofa disthese 0 erations is to most, t e so called silent or brush discharge and to avoid the disruptive types. To secure this result technically it has been the common practice to equip the solid conductor from which the discharge is to take place, such as groups 01' rows of needles orserrated metallic edges. I have discovered that from a practical standpoint all the advantages usually lic points,

facilitate, to the utsought by the use of such meta viz. ease of discharge of the electricity into the gas, may be obtained in much higher deree by the use of fine filaments or hairs orming a pubescent surface between the solid conductors and the gas, even though these hairs or filaments may consist of materials not ordinarily classed as good conductors of electricity; for example, it is perfectly possible to employ for this purpose such materials-as asbestos, cotton, wool, silk,

etc. These, although relatively poor con-" ductors, amply sufiice, under the usualcon- Specification of Letters Patent. Application filed July 18, 1908. Seriallto. 443,284.

have illustrated and de-,

that while they allor are dlscharge. The aimin suspende for example,

Patented Jam 11, i910.

ditions, and, if necessary, thematerial may be so treated as to increase its conductivity. My invention, therefore, consists in effecting the interchan e of the. electric charges between solid con uctors-and gases by bringing the conductors and gases into contact with one another at a pubescent surface.

It is to be understood that inthe resent specification and claims the term pu escent is not to be interpreted as including metallic wires or needles whose use in this connection is old, as I have above noted; but said term as herein used refers only to fine filaments of textile materials, such as are noted above by way of illustration.

tical forms in which my invention may be applied to industrial operations, I show in the accompanyin apparatus capab provement.

' Figure 1 is a view of a simple form of a pubescent electrode. Fig. 2 represents, schematically, an ozone generator, to which the pubescent electrodes may be applied. Fig. 3 represents an electrostatic ore-sepadrawlngs several kinds of ev of employing my imrator, to which my invention is applied.

Fig. 4 represents the application of my invention to the collectors of a Wimhurst influence-machine. Fig. 5 shows the application of m invention to the precipitation of particles from gaseous bodies, as the collection of zinc white in its ordinary manufacture, or the collection of fine dust produced by pulverizing mills with air elutriation.

In Fig-1, the pubescent electrode consists of a strand of filamentous material 1, as for example an ordinary cotton string whose surface has, if necessary, been roughened by brushing or gently scraping,

twisted or braided together with two stran s of metallic wire 2, in such wise that even should a break occur in the cotton it would be impossible for it to unwind. The choice of material both for the metallic wires and for the filamentous or pubescent strand 1,.

will naturally depend upon conditions under which the electrode must operate; parcellulose fibers would undergo disintegra- .tion and become useless.

In some such cases excellent results have been obtained by the substitution of asbestos for. the cotton. In other cases it has proved better to subject the cotton to carbonization out of contact with the air, either before or after combining it'with the metallic wires. This process may be so conducted, as to leave the structure of the cotton intact and still render it practically unaffected by even a strong acid reaction.

Fig. 2, which illustrates an ozone generator, consists of a tube 3, through which a current of air or oxygen is'passed, as indicated by the arrows, and within whose interior are stretched between the two insulating heads 4, a plurality of pubescent electrodes 1 of the above description. Some of these are connected electrically to one terminal 5 of a source of high voltage electricity 6. The remainder are insulated from these by the heads 4, and are connected to the other terminal 7 of the same source.

The tube 3 may be of either conducting or nonconductlng material. In the former case it may also be connected to one of the terminals 5 ,or 7, and may even serve as the sole conductor for one side of the high voltage. circuit. In this case all the pnbescent electrodes 1 may be connected to the opposite terminal. Then the discharge will be practically unidirectional, z. e. from the pubescent electrode to the smooth surface of the tube.

In Fig. 3,"which illustrates the application of my invention to an electrostatic ore separator, the metallic revolving roller 8 is electrically connected throu h its shaft and supporting bearing to eart at 9, .and receives a steady supply of the finely divided ore from the hopper 10. In front and somewhat above the center of this roller, parallel with its axis and insulated from it is stretcheda pubescent electrode in the form of a piece of cotton covered magnet wire 11. This takes the place of the metallic discharge points ordinarily employed, in the same relative position in machines of this type already in general use. The fibers of the insulation on the wire may be slightly roughened up, if necessary. 'The two terminals .of the source of high voltage electricity are connected respectively to earth and to t e wire 11. The receptacles 12 and 13'serve to catch the conductive and nonconductiveparticles respectively, or such as have different dielectric constants. The scraper 14 serves to remove from the roller all particles still adhering to it, at this pointinits revolution.

Fig 1 represents the application of the same principle at the collectors of a Wim-- hurst influence machine. In this device 15 and 16 are the oppositely rotating disks of" the machine, and 1.7 is a U-shaped piece of sheet metal to which, and projecting slightly over whose edges toward the disks, are cemented two strips 18 and 19 of cloth whose free edges, i. e. the edges towardthe disks are frayed out so as to present many 'fine filaments. These edges'may in some cases be serrated to advantage as indicated in the strip 19. The system of pubescent strips takes the place of the metallic collecting points of the ordinary Wimhurst machine, being supported and connected in the same manner as this latter; the other details of the machine being as usual.

Fig. 5 illustrates the application of the above method to) the precipitation of suspended particles from gaseous bodies as for example the collection of zinc white in its ordinary course of manufacture, or the collection of fine dust produced by pulverizing mills with air elutriationu The chamber 20 made of conductiiig material is connected to earth. The metallic rod 21 is held in place and insulated from the chamber by the bushing 22. The cord 1 of cotton, asbestos or similar material is wound spirally around.

leave through the exit pipe 24 free of suspended matter.

In the above descriptions the specific forms and construction of the pubescent electrodes have been described in each case by way of illustration, but it is not to be understood that these forms are the only ones practical nor that they are of necessity associated with or limited to the particular application in connection with which each has been described. It is the application of a pubescent surface to the solution of certain technical problems on an industrial scale that is the intention herein to claim.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is p 1. The improvement in effecting the interchange of electric charges between electrified solid conductors and gases which consists in bringing said electrified solid conductors and gases into contact with one another at a.

pubescent surface which forms a part 0; said tential between said solid conductors and the 10 solid conductor. body of gas.

2. The process of interchange of electric In testunony whereof have signed my charges between electrified solid conductors name to thls specificatlon 1n the presence of 5 and gases whlch consist in bringing said elec- 11W 0 Su scribing Witnesses.

trified solid oondctors and ases into c0n- FREDERICK GARDNER GOTTRELL. .tact with one a'no her. at a u escent surface Wltnesses: which forms a part of sai solid conductor, ANNA MoNErLL,

and producing a difference of electrical po- 0. CHENEY.. 

